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Barba-Lobo A, Gutiérrez-Álvarez I, Adame JA, San Miguel EG, Bolívar JP. Behavior of 222Rn, 220Rn and their progenies along a daily cycle for different meteorological situations: Implications on atmospheric aerosol residence times and Rn daughters' equilibrium factors. J Hazard Mater 2024; 464:132998. [PMID: 37988870 DOI: 10.1016/j.jhazmat.2023.132998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 10/31/2023] [Accepted: 11/11/2023] [Indexed: 11/23/2023]
Abstract
The correct assessment of the radiological hazard from radon and daughters, external and internal doses, residence times and equilibrium factors, implies the need to properly determine 222Rn (radon), 220Rn (thoron) and their respective short-lived progenies (214Pb and 214Bi, and 212Pb and 212Bi, respectively), where the precise measurements of both progenies are quite complex due to their very short half-lives. In addition, it is important to study the temporal behavior of all these radionuclides along daily cycles. Therefore, the aim of this study was to analyze the temporal evolution of radon, thoron and their progenies, and of their activity ratios along daily cycles for two different meteorological situations (synoptic and mesoscale processes). Radon and thoron were measured using a radon monitoring system, while their respective progenies were collected onto atmospheric filters using an ASS-500 sampler, and then measured by gamma-ray spectrometry. Furthermore, the different relationships between the concentrations of radionuclides and the different meteorological variables of interest (temperature, ABL height, and speed and direction of the wind) were found. Finally, the atmospheric aerosol residence times and Rn daughters' equilibrium factors were estimated for each sampling carried out along the two daily cycles, finding results consistent with previous studies.
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Affiliation(s)
- A Barba-Lobo
- Radiation Physics and Environment Group (FRYMA), Center for Natural Resources, Health and Environment (RENSMA), University of Huelva, 21007E Huelva, Spain; Department of Medical Radiation Sciences, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Gothenburg SE-413 45, Sweden.
| | - I Gutiérrez-Álvarez
- Radiation Physics and Environment Group (FRYMA), Center for Natural Resources, Health and Environment (RENSMA), University of Huelva, 21007E Huelva, Spain
| | - J A Adame
- Atmospheric Sounding Station - El Arenosillo, Atmospheric Research and Instrumentation Branch, National Institute for Aerospace Technology (INTA), Mazagón, Huelva, Spain
| | - E G San Miguel
- Radiation Physics and Environment Group (FRYMA), Center for Natural Resources, Health and Environment (RENSMA), University of Huelva, 21007E Huelva, Spain
| | - J P Bolívar
- Radiation Physics and Environment Group (FRYMA), Center for Natural Resources, Health and Environment (RENSMA), University of Huelva, 21007E Huelva, Spain
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Barba-Lobo A, Gutiérrez-Álvarez I, San Miguel EG, Bolívar JP. A methodology to determine 212Pb, 212Bi, 214Pb and 214Bi in atmospheric aerosols; Application to precisely obtain aerosol residence times and Rn-daughters' equilibrium factors. J Hazard Mater 2023; 445:130521. [PMID: 36463739 DOI: 10.1016/j.jhazmat.2022.130521] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 11/25/2022] [Accepted: 11/28/2022] [Indexed: 06/17/2023]
Abstract
Progeny of 222Rn and 220Rn, (212Pb, 212Bi, 214Pb and 214Bi) are essential to assess radiological hazard, external and internal doses, residence times and equilibrium factors. Precise measurements of these nuclides are quite complex due to their very short half-lives. This study outlines a new and precise methodology to measure these nuclides. Radon-222 and 220Rn were measured using a radon monitoring system, while their respective progenies were collected in an atmospheric filter using an ASS-500 sampler and measured by gamma-ray spectrometry. The 212Pb concentrations were very similar to the thoron ones, where all 212Bi/212Pb ratios were consistently less than 1. The relative uncertainties, σr, of the 212Pb and 212Bi activity concentrations, and 212Bi/212Pb activity ratio are generally less than 10%. Moreover, 214Pb/222Rn ratios were about 0.7, agreeing well with previous works. The σr for 214Pb, 214Bi and 214Bi/214Pb were generally less than 6%. This methodology was applied to estimate aerosol residence times using the 214Pb/222Rn and 212Bi/212Pb activity ratios, and to obtain equilibrium factors, achieving consistent results. Furthermore, the methodology consistency and validity range were studied with time elapsed between sampling end and counting start, and the sampling durations, finding the optimum times to precisely determine 212Pb, 212Bi, 214Pb and 214Bi.
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Affiliation(s)
- A Barba-Lobo
- Radiation Physics and Environment Group (FRYMA), Department of Integrated Sciences, Center for Natural Resources, Health and Environment (RENSMA), University of Huelva, 21007 Huelva, Spain.
| | - I Gutiérrez-Álvarez
- Radiation Physics and Environment Group (FRYMA), Department of Integrated Sciences, Center for Natural Resources, Health and Environment (RENSMA), University of Huelva, 21007 Huelva, Spain
| | - E G San Miguel
- Radiation Physics and Environment Group (FRYMA), Department of Integrated Sciences, Center for Natural Resources, Health and Environment (RENSMA), University of Huelva, 21007 Huelva, Spain
| | - J P Bolívar
- Radiation Physics and Environment Group (FRYMA), Department of Integrated Sciences, Center for Natural Resources, Health and Environment (RENSMA), University of Huelva, 21007 Huelva, Spain
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San Miguel EG, Hernández-Ceballos MA, García-Mozo H, Bolívar JP. Evidences of different meteorological patterns governing 7Be and 210Pb surface levels in the southern Iberian Peninsula. J Environ Radioact 2019; 198:1-10. [PMID: 30557786 DOI: 10.1016/j.jenvrad.2018.12.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 11/30/2018] [Accepted: 12/03/2018] [Indexed: 06/09/2023]
Abstract
7Be, 210Pb and PM10 levels in surface air have been simultaneously measured at two sampling sites in the southern Iberian Peninsula for a period of two years. Each site covers one different meteorological area of the Guadalquivir valley, from the mouth (Huelva) to the middle point (Cordoba). The objective of the present study is to analyse the spatial variability of both natural radionuclides, and to identify and characterise the meteorological patterns associated with similar and different surface concentration levels in this complex region. Concentrations are similar in both sampling sites. 7Be level is in the 0.6-15.5 mBq m-3 range in Huelva and 1.2-13.3 mBq m-3 in Córdoba, 210Pb activity concentrations are between 0.04 and 2.30 mBq m-3 in Huelva, and between 0.03 and 1.2 mBq m-3 in Cordoba, and PM10 concentrations are found to be in the 5.1-81.3 μg m-3 range in Huelva, and 8.2-76.3 μg m-3 in Cordoba, respectively. A linear regression analysis indicates more regional variability for 210Pb than for 7Be between simultaneous measurements. Principal components analysis (PCA) is applied to the datasets and the results reveal that aerosol behaviour is mainly represented by two components, which explain 82% of the total variance. The analysis of surface measurements and meteorological parameters revealed that component F1 groups sampling periods in which the influence of similar meteorological conditions over the region lead to similar 7Be, 210Pb and PM10 concentration levels in both sampling sites. On the other hand, component F2 detaches the 7Be, 210Pb and PM10 concentration levels between monitoring sites, and the meteorological analysis shows how surface concentrations within this component are associated with the development of different mesoscale circulations in each part of the valley. The identification of sampling periods characterised by differences in surface concentrations and wind patterns between stations suggests that the valley could not be considered as one single unit for certain meteorological scenarios. These results evidence how the understanding of wind characteristics within a complex terrain provide some essential knowledge in the regionalization and/or optimization of monitoring networks.
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Affiliation(s)
- E G San Miguel
- Department of Integrated Sciences, Area of Applied Physics, University of Huelva, 21071, Huelva, Spain; Research Center on Natural Resources, Health and the Environment (RENSMA), University of Huelva, 21071, Huelva, Spain.
| | | | - H García-Mozo
- Department of Botany, Ecology and Plant Physiology, Agrifood, Campus of International Excellence (CeiA3), University of Córdoba, Córdoba, Spain
| | - J P Bolívar
- Department of Integrated Sciences, Area of Applied Physics, University of Huelva, 21071, Huelva, Spain; Research Center on Natural Resources, Health and the Environment (RENSMA), University of Huelva, 21071, Huelva, Spain
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Pérez-Moreno SM, Gázquez MJ, Casas-Ruiz M, San Miguel EG, Bolívar JP. An improved method for radium-isotopes quartet determination by alpha-particle spectrometry by using 225Ra ( 229Th) as isotopic tracer. J Environ Radioact 2019; 196:113-124. [PMID: 30447554 DOI: 10.1016/j.jenvrad.2018.11.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 10/04/2018] [Accepted: 11/09/2018] [Indexed: 06/09/2023]
Abstract
A new method for the determination of radium quartet (223,224,226,228Ra) in environmental samples by alpha-particle spectrometry with PIPS detectors is described. This uses 225Ra as yield tracer, in equilibrium at the beginning with 229Th. Thorium is removed from the sample by using AG1X8 anion-resin, and then radium isotopes are isolated and purified with a cation-exchange column Biorad AG50X8, verifying that Ac has been fully removed from the sample to ensure the good evaluation of the Ra yield (average decontamination factor > 92%). Finally, the counting source of radium is obtained by micro-precipitation with BaSO4. This method produces high spectral resolution (<35 keV), and quantitative Ra recoveries (>70%). In this new method, NH4Ac in 0.1 M HNO3 is used to remove the 225Ac contained in the sample in order to avoid its future spectral interference in the yield calculation. The method has been validated by using certified reference samples with known concentrations of radium isotopes.
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Affiliation(s)
- S M Pérez-Moreno
- Department of Applied Physics, University of Huelva, Huelva, Spain
| | - M J Gázquez
- Department of Applied Physics, University of Cadiz, Cadiz, Spain
| | - M Casas-Ruiz
- Department of Applied Physics, University of Cadiz, Cadiz, Spain
| | - E G San Miguel
- Department of Applied Physics, University of Huelva, Huelva, Spain
| | - J P Bolívar
- Department of Applied Physics, University of Huelva, Huelva, Spain.
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Abril JM, San Miguel EG, Ruiz-Canovas C, Casas-Ruiz M, Bolívar JP. From floodplain to aquatic sediments: Radiogeochronological fingerprints in a sediment core from the mining impacted Sancho Reservoir (SW Spain). Sci Total Environ 2018; 631-632:866-878. [PMID: 29727997 DOI: 10.1016/j.scitotenv.2018.03.114] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 03/08/2018] [Accepted: 03/10/2018] [Indexed: 06/08/2023]
Abstract
The Sancho Reservoir (SW Spain) was built in 1962, about the time of maximum 137Cs fallout, and it has been affected by acid mine drainage (AMD) particularly since the mining cease in 2001. This is a unique scenario for studying the radiogeochronological fingerprints in AMD-affected sediments deposited over the former flood plain. A sediment core sampled in 2011 was analysed for bulk density, 137Cs, 239Pu, 240Pu, 210Pb, 226Ra, 228Ra, 234Th (238U) and 40K, and studied with various radiometric dating models. Bulk density revealed unsteady compaction and likely depositional events. The activity concentrations of 226Ra, 228Ra, 234Th (238U) and 40K were uniform down-core, but declining overall in the upper 0-25cm, revealing changes in provenance except for 238U, which increased in the top 10cm likely due to its supply by AMD. The AMD fingerprint was also found in the 239+240Pu/137Cs activity ratio, which increased in the top sediment layers. The 137Cs and 239+240Pu profiles show well defined peaks at the same depth, with inventories being about four times higher than the expected integrated atmospheric deposition in the area. The unsupported 210Pb (210Pbexc) showed a complex non-monotonic profile interrupted at several sections, particularly around the 137Cs peak. The whole dataset cannot be interpreted in terms of continuous sedimentation processes. Based upon correlated features in the bulk density and 210Pbexc profiles, a series of depositional events (likely linked to peaks in the rainfall records) have been identified in the core. These events date back to the period comprised since the construction of the dam until its increase in height in 1972, which likely displaced upstream the main depositional area of riverine loads, as inferred from sediment trap data. The CRS (with a reference date) and (a piecewise) CIC models have been used for complementing and discussing the chronology.
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Affiliation(s)
- J M Abril
- Department of Applied Physics I, ETSIA, University of Seville, Spain.
| | - E G San Miguel
- Department of Integrated Sciences, Area of Applied Physics, University of Huelva, Campus de El Carmen, 21071 Huelva, Spain; Research Center on Natural Resources, Health and the Environment (RENSMA), University of Huelva, 21071 Huelva, Spain
| | - C Ruiz-Canovas
- Department of Earth Sciences, Faculty of Experimental Sciences, University of Huelva, Spain; Research Center on Natural Resources, Health and the Environment (RENSMA), University of Huelva, 21071 Huelva, Spain
| | - M Casas-Ruiz
- Department of Applied Physics, University of Cadiz, Spain
| | - J P Bolívar
- Department of Integrated Sciences, Area of Applied Physics, University of Huelva, Campus de El Carmen, 21071 Huelva, Spain; Research Center on Natural Resources, Health and the Environment (RENSMA), University of Huelva, 21071 Huelva, Spain
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Cánovas CR, Olías M, Macias F, Torres E, San Miguel EG, Galván L, Ayora C, Nieto JM. Water acidification trends in a reservoir of the Iberian Pyrite Belt (SW Spain). Sci Total Environ 2016; 541:400-411. [PMID: 26410715 DOI: 10.1016/j.scitotenv.2015.09.070] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 09/14/2015] [Accepted: 09/14/2015] [Indexed: 06/05/2023]
Abstract
Scarcity of waters is the main limiting factor of economic development in most arid and semi-arid regions worldwide. The construction of reservoirs may be an optimal solution to assure water availability if the drainage area shows low disturbances. This is the quandary of mining areas where economic development relies on water accessibility. Water acidification trends were investigated in the Sancho Reservoir (SW Spain) in the last 20 years. The acidity (pH3-5) and high dissolved metal concentrations (e.g., 4.4 mg/L of Al, 2.1mg/L of Mn, 1.9 mg/L of Zn) observed in the Sancho, together with the large volume stored (between 37 and 55 Mm(3)), makes this reservoir an extreme case of surface water pollution worldwide. A progressive acidification has been observed since 2003, as evidenced by decreasing pH values and increasing dissolved metal concentrations, especially noticeable after 2007. The increase in the net acidity in the reservoir originates from the higher input of metals and acidity due to the rebound effect after the mining closure in 2001. This trend was not detected in the river feeding the reservoir due to its great hydrological and hydrochemical variability, typical of the Mediterranean climate. Chemical analysis and absolute dating of sediments identified a progressive enrichment in S and metals (i.e., Fe, Zn Cu, Ni, Co and Cd) in the upper 20 cm, which reinforce the year 2002/03 as the onset of the acidification of the reservoir. The decrease of pH values from 4-5 to 3-4 occurred later than the increase in sulfate and metals due to pH-buffering by Al. The acid mine drainage (AMD) pressure has caused an increment of dissolved Fe and other metals, as well as a change in the pH buffering role, exerted now by Fe. These processes were simulated by PHREEQC, which confirms that the acidification trend will continue, causing pH values to reach 2.5 if AMD pressure persists.
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Affiliation(s)
- C R Cánovas
- Department of Geology, Faculty of Experimental Sciences, University of Huelva, Campus el Carmen s/n, 21071 Huelva, Spain.
| | - M Olías
- Department of Geodynamics and Paleontology, Faculty of Experimental Sciences, University of Huelva, Campus el Carmen s/n, 21071 Huelva, Spain
| | - F Macias
- Department of Geology, Faculty of Experimental Sciences, University of Huelva, Campus el Carmen s/n, 21071 Huelva, Spain
| | - E Torres
- Institute of Environment Assessment and Water Research (IDAEA), CSIC, C/Jordi Girona 18-26, 08034 Barcelona, Spain
| | - E G San Miguel
- Department of Applied Physics, Faculty of Experimental Sciences, University of Huelva, Campus el Carmen s/n, 21071 Huelva, Spain
| | - L Galván
- Department of Geodynamics and Paleontology, Faculty of Experimental Sciences, University of Huelva, Campus el Carmen s/n, 21071 Huelva, Spain
| | - C Ayora
- Institute of Environment Assessment and Water Research (IDAEA), CSIC, C/Jordi Girona 18-26, 08034 Barcelona, Spain
| | - J M Nieto
- Department of Geology, Faculty of Experimental Sciences, University of Huelva, Campus el Carmen s/n, 21071 Huelva, Spain
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Lozano RL, Hernández-Ceballos MA, Adame JA, Casas-Ruíz M, Sorribas M, San Miguel EG, Bolívar JP. Radioactive impact of Fukushima accident on the Iberian Peninsula: evolution and plume previous pathway. Environ Int 2011; 37:1259-1264. [PMID: 21683442 DOI: 10.1016/j.envint.2011.06.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 05/31/2011] [Accepted: 06/01/2011] [Indexed: 05/30/2023]
Abstract
High activity concentrations of several man-made radionuclides (such as (131)I, (132)I, (132)Te, (134)Cs and (137)Cs) have been detected along the Iberian Peninsula from March 28th to April 7th 2011. The analysis of back-trajectories of air masses allowed us to demonstrate that the levels of manmade radionuclide activity concentrations in the southwest of the Iberian Peninsula come from the accident produced in the nuclear power plant of Fukushima. The pathway followed by the radioactive plume from Fukushima into Huelva (southwest of the Iberian Peninsula) was deduced through back-trajectories analysis, and this fact was also verified by the activity concentrations measured of those radionuclides reported in places crossed by this radioactive cloud. In fact, activity concentrations reported by E.P.A., and by IAEA, in several places of Japan, Pacific Ocean and United States of America are according to the expected ones from the air mass trajectory arriving at Huelva province.
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Affiliation(s)
- R L Lozano
- Department of Applied Physics, University of Huelva, Spain
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Lozano RL, San Miguel EG, Bolívar JP, Baskaran M. Depositional fluxes and concentrations of7Be and210Pb in bulk precipitation and aerosols at the interface of Atlantic and Mediterranean coasts in Spain. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2011jd015675] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Lozano RL, San Miguel EG, Bolívar JP. Assessment of the influence of in situ210Bi in the calculation of in situ210Po in air aerosols: Implications on residence time calculations using210Po/210Pb activity ratios. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2010jd014915] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Mas JL, San Miguel EG, Bolívar JP, Vaca F, Pérez-Moreno JP. An assay on the effect of preliminary restoration tasks applied to a large TENORM wastes disposal in the south-west of Spain. Sci Total Environ 2006; 364:55-66. [PMID: 16343599 DOI: 10.1016/j.scitotenv.2005.11.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2005] [Revised: 10/27/2005] [Accepted: 11/03/2005] [Indexed: 05/05/2023]
Abstract
A large industrial wastes disposal site, where two phosphate rock processing plants release their wastes, located close to Huelva town (SW of Spain), has been partially submitted to restoration as a preliminary step in a possible decomissioning process. Due to the high natural radioactivity contents of these wastes, this repository is considered as a radiological anomaly, being actually considered as TENORM (technically enhanced naturally occurring radioactive materials). The efficiency of this restoration from the radiological point of view according to the new European regulatory framework was evaluated in this work. The results allow to conclude that, as a consequence of the partial restoration works, the external dose rate has been drastically reduced above the repository system. Nevertheless, special attention must be paid on the occupational factor to be applied to workers on the unrestored system. The application of a dosimetric model allows the prediction of the negative effects of using certain industrial wastes as a cover system in this restoration/mitigation task.
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Affiliation(s)
- J L Mas
- Dpto Física Aplicada I, Universidad de Sevilla, Avda. Reina Mercedes s/n, 41012-Sevilla, Spain
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San Miguel EG, Perez-Moreno JP, Bolivar JP, García-Tenorio R. A semi-empirical approach for determination of low-energy gamma-emmiters in sediment samples with coaxial Ge-detectors. Appl Radiat Isot 2004; 61:361-6. [PMID: 15177372 DOI: 10.1016/j.apradiso.2004.03.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A simple method for the determination in sediment samples of low-energy gamma-emitters with coaxial Ge detectors and using a cylindrical sample geometry is outlined. This method allows an easy estimation of self-absorption effects by knowing the apparent densities and the composition of the investigated samples. As calibration matrixes solid samples enriched in known amounts of natural radionuclides emitting low-energy gamma rays were used. In this way, the difficult homogenisation steps needed when liquid spikes are added to a solid blank for manufacturing the calibration sample are avoided. The method has been carefully checked and validated by applying it to sediment samples with known activities of some low-energy gamma-ray emitters. Additionally, these sediment measurements have allowed to evaluate the magnitude and importance of the self-absorption corrections.
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Affiliation(s)
- E G San Miguel
- Departamento de Física Aplicada, EPS La Rábida, 21819-Palos, Huelva, Spain
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San Miguel EG, Bolívar JP, García-Tenorio R. Vertical distribution of Th-isotope ratios, 210Pb, 226Ra and 137Cs in sediment cores from an estuary affected by anthropogenic releases. Sci Total Environ 2004; 318:143-57. [PMID: 14654281 DOI: 10.1016/s0048-9697(03)00367-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
In an estuary system highly polluted by mining and industrial activities, the sections of sediment cores affected by anthropogenic inputs of U-series radionuclides (due to fertilizer plants releases) were determined through the vertical profiles of Th-isotopic ratio (230Th/232Th). Also, when possible, a modified version of the 210Pb dating method was applied in the uncontaminated sections of these cores. Using the information provided by the Th-isotopic ratio and 210Pb methods, we were able to establish confident chronologies, covering the last century, in several of the analysed sediment cores. These chronologies will be used in forthcoming research to study the time evolution of pollutant concentrations in the estuary. Additionally, and based on the established chronologies, we have found that sedimentation rates have drastically increased in some zones of the estuary since the commencement of several industrial activities in the surrounding environment and since the construction of two dikes in the area.
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Affiliation(s)
- E G San Miguel
- Departamento Física Aplicada, E.P.S. La Rábida, Ctra Palos S/N, Huelva 21819, Spain.
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San Miguel EG, Pérez-Moreno JP, Bolívar JP, García-Tenorio R. Validation of isotope signatures in sediments affected by anthropogenic inputs from uranium series radionuclides. Environ Pollut 2003; 123:125-130. [PMID: 12663212 DOI: 10.1016/s0269-7491(02)00340-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
This paper aims to show the usefulness of 226Ra/228Ra activity ratios and confirm the possibility of using 230Th/232Th activity ratios as chronological markers in sediment cores from an estuarine system strongly contaminated by discharges from non-nuclear industries (fertiliser plants). The validation was carried out using an independent, well-established dating technique based on the analysis of the 137Cs fallout profile, which comprises the same time interval as that covered by both isotope ratios. The advantage of using the 226Ra/228Ra activity ratio profile instead of the Th-isotope profile is that determination can be accomplished with a non-destructive, simpler and less time-consuming technique, because both Ra isotopes can be determined by gamma-ray spectrometry.
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Affiliation(s)
- E G San Miguel
- Dpto Física Aplicada, EPS La Rábida, Universidad de Huelva, 21819-Palos, Huelva, Spain.
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San Miguel EG, Bolívar JP, García-Tenorio R, Martín JE. 230Th/232Th activity ratios as a chronological marker complementing 210Pb dating in an estuarine system affected by industrial releases. Environ Pollut 2001; 112:361-368. [PMID: 11291442 DOI: 10.1016/s0269-7491(00)00146-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The main purpose of this research is to show the usefulness of the 230Th/232Th activity ratios as a chronological marker that can be helpful in the dating of sediment cores collected from an estuarine system located in the south west of Spain highly polluted by wastes from fertilizer plants. These wastes, being released for 30 years, and enriched in radionuclides from the uranium series including 210Pb, invalidate the application of the 210Pb dating technique in full extent to the sediment cores collected in this estuary. However, the evaluation and the interpretation of both 210Pb and 230Th/232Th profiles allows the determination of average sedimentation rates in different parts of the cores, contaminated and noncontaminated zone, that agree in the case analysed in this research. Through this approach, a confident chronology covering the last century, which is essential to analyse and reconstruct the historical evolution of other pollutants in this heavily contaminated system can be established.
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Affiliation(s)
- E G San Miguel
- Departamento de Física Aplicada, EPS La Rábida, 21819-Palos, Huelva, Spain.
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Más JL, Bolívar JP, García-Tenorio R, Aguado JL, San Miguel EG, González-Labajo J. A dosimetric model for determining the effectiveness of soil covers for phosphogypsum waste piles. Health Phys 2001; 80:34-40. [PMID: 11204114 DOI: 10.1097/00004032-200101000-00007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Phosphogypsum (PG) is a by-product of the phosphoric acid production process that contains high concentrations of U-series radionuclides. PG piles formed during the last 30 years cover about 1,200 hectares and are located close to the town of Huelva (Spain) on a salt-marsh. The regional government of Andalusia restored the area beginning in 1990 by covering it with a 25-cm-thick layer of natural soil. With this restoration, the external gamma-dose rate in the zone has decreased drastically, approaching near environmental background values. This conclusion is based on results obtained through in-situ monitoring measurements and through a dosimetric model developed for that particular radiation source. As the model uses average parameters of the studied site, its output does not show a correlation point by point with the in-situ monitoring measurements. However, a good agreement is observed in average values over the covered piles. The model gives an average dose rate of 0.41 mGy y(-1) and the in situ monitoring 0.40 mGy y(-1). Based on this model, it is possible to calculate the necessary thickness of soil to reduce the dosimetric contribution from a similar extension of PG until the desired level is reached. In our conditions, in a 25-cm-thick soil, about 0.19 mGy y(-1) is the increase produced by the PG layer in relation to an infinitum soil layer. Consequently, no radiological concern exists in the restored zones with respect to the external gamma radiation.
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Affiliation(s)
- J L Más
- Department Física Aplicada, E.P.S. La Rábida, Universidad de Huelva, Spain
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